Ecotoxicology

, Volume 21, Issue 3, pp 832–846

Assessment of toxicity and potential risk of the anticoagulant rodenticide diphacinone using Eastern screech-owls (Megascops asio)

Authors

    • Patuxent Wildlife Research CenterU.S. Geological Survey
  • Katherine E. Horak
    • U.S. Department of Agriculture, National Wildlife Research Center
  • Rebecca S. Lazarus
    • Patuxent Wildlife Research CenterU.S. Geological Survey
  • Karen M. Eisenreich
    • Patuxent Wildlife Research CenterU.S. Geological Survey
  • Carol U. Meteyer
    • U.S. Geological Survey, National Wildlife Health Center
  • Steven F. Volker
    • U.S. Department of Agriculture, National Wildlife Research Center
  • Christopher M. Campton
    • U.S. Department of Agriculture, National Wildlife Research Center
  • John D. Eisemann
    • U.S. Department of Agriculture, National Wildlife Research Center
  • John J. Johnston
    • U.S. Department of Agriculture, Food Safety and Inspection Service
Article

DOI: 10.1007/s10646-011-0844-5

Cite this article as:
Rattner, B.A., Horak, K.E., Lazarus, R.S. et al. Ecotoxicology (2012) 21: 832. doi:10.1007/s10646-011-0844-5

Abstract

In the United States, new regulatory restrictions have been placed on the use of some second-generation anticoagulant rodenticides. This action may be offset by expanded use of first-generation compounds (e.g., diphacinone; DPN). Single-day acute oral exposure of adult Eastern screech-owls (Megascops asio) to DPN evoked overt signs of intoxication, coagulopathy, histopathological lesions (e.g., hemorrhage, hepatocellular vacuolation), and/or lethality at doses as low as 130 mg/kg body weight, although there was no dose–response relation. However, this single-day exposure protocol does not mimic the multiple-day field exposures required to cause mortality in rodent pest species and non-target birds and mammals. In 7-day feeding trials, similar toxic effects were observed in owls fed diets containing 2.15, 9.55 or 22.6 ppm DPN, but at a small fraction (<5%) of the acute oral dose. In the dietary trial, the average lowest-observed-adverse-effect-level for prolonged clotting time was 1.68 mg DPN/kg owl/week (0.24 mg/kg owl/day; 0.049 mg/owl/day) and the lowest lethal dose was 5.75 mg DPN/kg owl/week (0.82 mg/kg owl/day). In this feeding trial, DPN concentration in liver ranged from 0.473 to 2.21 μg/g wet weight, and was directly related to the daily and cumulative dose consumed by each owl. A probabilistic risk assessment indicated that daily exposure to as little as 3–5 g of liver from DPN-poisoned rodents for 7 days could result in prolonged clotting time in the endangered Hawaiian short-eared owl (Asio flammeus sandwichensis) and Hawaiian hawk (Buteo solitarius), and daily exposure to greater quantities (9–13 g of liver) could result in low-level mortality. These findings can assist natural resource managers in weighing the costs and benefits of anticoagulant rodenticide use in pest control and eradication programs.

Keywords

RodenticidesBirdsClotting timeDiphacinoneSecondary poisoning

Supplementary material

10646_2011_844_MOESM1_ESM.pdf (14 kb)
Supplementary material 1 (PDF 15 kb)

Copyright information

© Springer Science+Business Media, LLC (outside the USA) 2012